There is provided a method of controlling a mobile manipulator for tracking a surface. The mobile manipulator includes a mobile base movable in an axial direction of the mobile manipulator and a manipulator supported on the mobile base having an end effector adjustable in a lateral direction of the mobile manipulator. The method includes detecting the surface from the mobile manipulator, including positions of the surface at points along the surface, determining a reference path for the end effector to track based on an offset from the surface detected, determining a tracking error in the reference path determined, and adjusting a position of the end effector in the lateral direction based on the tracking error to compensate for the tracking error in the reference path determined. There is also provided a corresponding mobile manipulator.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of controlling a mobile manipulator for tracking a surface, the mobile manipulator comprising a mobile base movable in an axial direction of the mobile manipulator and a manipulator supported on the mobile base having an end effector adjustable in a lateral direction of the mobile manipulator, the method comprising: detecting the surface from the mobile manipulator, including positions of the surface at points along the surface; determining a reference path for the end effector to track based on an offset from the surface detected; determining a tracking error between the reference path determined and the mobile manipulator; and adjusting a position of the end effector in the lateral direction based on the tracking error to compensate for the tracking error in the reference path determined.
2. The method according to claim 1 , wherein said detecting the surface comprises determining the positions of the surface at points along the surface with respect to the mobile manipulator in a coordinate system of the mobile manipulator.
3. The method according to claim 2 , wherein said determining the positions of the surface at points along the surface comprises: obtaining point cloud data of the surface in the coordinate system of the mobile manipulator; and detecting a line from the point cloud data corresponding to the surface, wherein the line indicates the positions of the surface at points along the surface.
4. The method according to claim 3 , wherein said detecting a line from the point cloud data comprises detecting the line based on a Hough Transform technique.
5. The method according to claim 1 , wherein the offset is a predetermined distance.
6. The method according to claim 1 , wherein the tracking error comprises a distance error, and said determining a tracking error comprises determining the distance error based on the snake detected and a position of the mobile manipulator obtained.
7. The method according to claim 6 , wherein said determining the distance error comprises determining a distance between the surface detected and the position of the mobile manipulator obtained and applying a filter technique based on said distance and a noise factor to obtain the distance error, wherein the noise factor represents a measurement noise in detecting the surface from the mobile manipulator.
8. The method according to claim 7 , wherein the filter technique is based on a Kalman filter.
9. The method according to claim 6 , wherein said detecting the surface further comprises detecting orientations of the surface at points along the surface, and wherein the tracking error further comprises an orientation error, and said determining a tracking error further comprises determining the orientation error based on the surface detected and an orientation of the mobile manipulator obtained.
10. The method according to claim 9 , further comprises: controlling the mobile base to track the reference path; and adjusting an orientation of the mobile base based on the orientation error determined.
11. The method according to claim 10 , wherein said adjusting an orientation of the mobile base comprises controlling a sensitivity of said adjusting based on the distance error.
12. The method according to claim 1 , wherein the end effector is further adjustable along a vertical axis or a vertical plane of the mobile manipulator, the vertical axis or the vertical plane being substantially perpendicular to the lateral direction.
13. A mobile manipulator for tracking a surface, the mobile manipulator comprising: a mobile base movable in an axial direction of the mobile manipulator; a manipulator supported on the mobile base having an end effector adjustable in a lateral direction of the mobile manipulator; and a controller configured for controlling the mobile base and the manipulator, the controller comprising at least one processor to: detect the surface from the mobile manipulator, including positions of the surface at points along the surface; determine a reference path for the end effector to track based on an offset from the surface detected; determine a tracking error between the reference path determined and the mobile manipulator; and adjust a position of the end effector in the lateral direction based on the tracking error to compensate for the tracking error in the reference path determined.
14. The mobile manipulator according to claim 13 , wherein to detect the surface from the mobile manipulator the at least one processor is further to determine the positions of the surface at points along the surface with respect to the mobile manipulator in a coordinate system of the mobile manipulator.
15. The mobile manipulator according to claim 14 , wherein to detect the surface from the mobile manipulator at least one processor is further to: obtain point cloud data of the surface in the coordinate system of the mobile manipulator; and detect a line from the point cloud data of the surface, wherein the line indicates the positions of the surface at points along the surface.
16. The mobile manipulator according to claim 13 , wherein the tracking error comprises a distance error, and wherein to determine the tracking error in the reference path determined the at least one processor is further to determine the distance error based on the surface detected and a position of the mobile manipulator obtained.
17. The mobile manipulator according to claim 16 , wherein to determine the distance error the at least one processor is further to determine a distance between the surface detected and the position of the mobile manipulator obtained and apply a filter technique based on said distance and a noise factor to obtain the distance error, wherein the noise factor represents a measurement noise in detecting the surface from the mobile manipulator.
18. The mobile manipulator according to claim 16 , wherein to detect the surface from the mobile manipulator the at least one processor is further to detect orientations of the surface at points along the surface, and wherein the tracking error further comprises an orientation error, and the tracking error determining module is further configured to determine the orientation error based on the surface detected and an orientation of the mobile manipulator obtained.
19. The mobile manipulator according to claim 18 , wherein the the at least one processor is further to control the mobile base to track the reference path, and wherein to adjust a position of the end effector in the lateral direction the at least one processor is further to adjust an orientation of the mobile base based on the orientation error determined.
20. A non-transitory computer-readable storage medium storing thereon a computer program product comprising instructions executable by one or more computer processors to perform a method of controlling a mobile manipulator for tracking a surface, the mobile manipulator comprising a mobile base movable in an axial direction of the mobile manipulator and a manipulator supported on the mobile base having an end effector adjustable in a lateral direction of the mobile manipulator, the method comprising: detecting the surface from the mobile manipulator, including positions of the surface at points along the surface; determining a reference path for the end effector to track based on an offset from the surface detected; determining a tracking error between the reference path determined and the mobile manipulator; and adjusting a position of the end effector in the lateral direction based on the tracking error to compensate for the tracking error in the reference path determined.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
February 1, 2016
April 14, 2020
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